1. Technical Field
This invention relates to missile tracking systems and, more particularly, to a missile tracking system with two track links having distinct frequencies.
2. Discussion
Some missiles, such as tube-launched, optically-tracked, wire-guided (TOW) missiles, do not include on-board tracking electronics and therefore require the input of target tracking signals from remotely located tracking electronics. Such missile systems typically include a target designator which defines a boresight or line of sight (LOS) from a launching site to a target. When the missile is fired, the tracking electronics guide the missile down the boresight to the target using a closed-loop control strategy. In other words, as the missile moves away from the boresight defined by the target designator, the error signal generated by the tracking electronics increases proportionately. As the missile moves towards the boresight defined by the target designator, the error signal decreases proportionately.
For tracking purposes, some missiles generate an optical beacon at near-infrared wavelengths which is received by tracking electronics associated with the aircraft. Still other missiles employ radar tracking. The tracking electronics generate azimuth and elevation error signals by identifying the displacement of the missile from the boresight. The tracking electronics transform the error signals from the launching site coordinate system, such as an aircraft coordinate system, to the missile coordinate system. The tracking electronics amplify the error signals and transmit the error signals to the missile. This closed-loop control continues to guide the missile down the boresight until the missile hits the target.
Some targets, however, are protected by electro-optical jammers which transmit high intensity signals at near-infrared wavelengths. If the jamming signal has an amplitude higher than the amplitude of the beacon generated by the missile, the tracking electronics can be confused by the electro-optical jamming signal. If the jamming signal is successful, the tracking electronics will incorrectly identify the displacement of the missile relative to the boresight. As a result, the error signals generated by the tracking electronics are incorrect and the missile will be guided away from both the boresight and, more importantly, the target. Common battlefield conditions such as smoke also degrade the optical beacon generated by the missile and cause incorrect error signals to be generated by the tracking electronics.
Therefore, a missile system which reduces the effects of electro-optical jamming and/or battlefield conditions such as smoke is desirable.
As cuts in the military budget continue, competitive pressure increases to provide missile tracking systems with higher reliability and increased accuracy at lower cost. Therefore, a missile system which reduces the effects of electro-optical jamming and/or battlefield conditions such as smoke without substantially increasing the cost of the missile tracking system is also desirable.